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The Southern H II region discovery Survey. II. The Full Catalog

journal contribution
posted on 2023-05-21, 12:09 authored by Wenger, TV, Dawson, JR, John DickeyJohn Dickey, Jordan, CH, McClure-Griffiths, NM, Anderson, LD, Armentrout, WP, Balser, DS, Bania, TM
The Southern H ii Region Discovery Survey (SHRDS) is a 900 hr Australia Telescope Compact Array 4-10 GHz radio continuum and radio recombination line (RRL) survey of Galactic H ii regions and infrared-identified H ii region candidates in the southern sky. For this data release, we reprocess all previously published SHRDS data and include an additional ~450 hr of observations. The search for new H ii regions is now complete over the range 259 < l < 346 , |b| < 4 for H ii region candidates with predicted 6 GHz continuum peak brightnesses >=30 mJy beam-1. We detect radio continuum emission toward 730 targets altogether including previously known nebulae and H ii region candidates. By averaging ~18 RRL transitions, we detect RRL emission toward 206 previously known H ii regions and 436 H ii region candidates. Including the northern sky surveys, over the last decade the H ii Region Discovery Surveys have more than doubled the number of known Galactic H ii regions. The census of H ii regions in the Wide-field Infrared Survey Explorer (WISE) Catalog of Galactic H ii Regions is now complete for nebulae with 9 GHz continuum flux densities >=250 mJy. We compare the RRL properties of the newly discovered SHRDS nebulae with those of all previously known H ii regions. The median RRL FWHM line width of the entire WISE Catalog H ii region population is 23.9 km s-1 and is consistent between Galactic quadrants. The observed Galactic longitude-velocity asymmetry in the population of H ii regions probably reflects underlying spiral structure in the Milky Way.


Publication title

Astrophysical Journal, Supplement Series



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School of Natural Sciences


Univ Chicago Press

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1427 E 60Th St, Chicago, USA, Il, 60637-2954

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